The 'Science' journal is publishing today in their September 1 issue a
theoretical study (see Abstract and Introductory and concluding parts of
that paper directly below) that predicts a decline in bird population as a
result of herbicide-tolerant sugar beets. Responses from Monsanto and
Biotechnology Industry Organization to that study is included below.
Predictions of Biodiversity Response to Genetically Modified
A. R. Watkinson, 1 * R. P. Freckleton, 1 Ý R. A. Robinson, 2 W. J.
www.sciencemag.org SCIENCE VOL 289 1 SEPTEMBER 2000 p1554-6
We simulated the effects of the introduction of genetically modified
herbicide tolerant (GMHT) crops on weed populations and the consequences
for seed eating birds. We predict that weed populations might be reduced
to low levels or practically eradicated, depending on the exact form of
management. Consequent effects on the local use of fields by birds might
be severe, because such reductions represent a major loss of food
resources. The regional impacts of GMHT crops are shown to depend on
whether the adoption of GMHT crops by farmers covaries with current weed
1 Schools of Environmental and Biological Sciences, University of East
Anglia, Norwich NR4 7TJ, UK. 2 Brit-ish Trust for Ornithology, The
Nunnery, Thetford, Norfolk IP24 2PU, UK. *To whom correspondence should be
addressed. E- mail: email@example.com
There is a growing research interest in the potential effects of the
release of genetically modified (GM) crops (1) on biodiversity. This is
prompted by concerns relating to the direct impact of GM crops on target
organ-isms and the indirect effects on the wider environment. The
environmental debate has to be set within a biodiversity landscape that is
already affected by the intensification of agriculture (2). Although, in
some senses, the introduction of GM crops may be no different than the
introduction of any other technology that leads to the further
intensification of agriculture, this new technology might offer a uniquely
rapid increase in intensification. We modeled the effects of the
introduction of a herbicide-resistant sugar beet (a spring-sown crop grown
throughout Europe and North America) on the population dynamics of an
annual weed, Chenopodium al-bum.
This weed occurs worldwide, and its seeds are an important source of food
for farmland birds (3, 4). We asked two questions: How do weed populations
respond to changing the efficiency and mode of weed control, and what
impact will the introduction of GMHT crops have on biodiversity and,
specifically, a seed-eating bird, the skylark (Alauda arvensis)? We based
our analysis on a model of the population dynamics of C. album in the
sugar beet that predicts the change in plant and seed bank numbers from
one sugar beet crop to the next (5) (Table 1). We modeled a five-course
rotation where sugar beet is grown every fifth year, with winter cereals
grown in the other 4 years. C. album can establish only every fifth year,
when sugar beet is grown. Between sugar beet crops, populations of C.
album persist in the form of a dormant seed pool. Seeds germinate in the
spring, and survival from germination to flowering in the autumn is
determined by herbicidal and mechanical control. In conventional systems,
this control is modeled through a parameter q, defined as the proportion
of plants that survive control (all plants survive control when q 5 1, and
none survive when q 5 0). Seed production is a function of competition for
resources during growth between individual weed plants (density
dependence) and the crop.
Our ability to predict the impact of GM technology on biodiversity
therefore depends critically not only on an under-standing of how the
ecological system will respond to technological change at a local scale,
but also on how the farming community will respond. Although the model
that we have developed is very simple, we think that it is generic for
weeds, seed-eating birds, and, indeed, for any technological innovation.
Summary: **FARMERS, BIRDS, AND GM CROPS: The use of genetically modified
herbicide-tolerant (GMHT) crops may severely reduce bird populations on a
small percentage of farms while having little effect on most others,
predicts a British study. Overall, the consequences should depend upon
which farmers adopt the new crop types, the study's authors conclude.
Andrew Watkinson and colleagues used a numerical model to investigate some
of the consequences of the changed herbicide use likely to be associated
with GMHT crops. According to the results, weed seed populations can be
expected to decline by at least 90% in some cases. Such a decline should
seriously reduce the numbers of skylarks using these fields, the study
suggests. In a related Perspective article, Les Firbank and Frank Forcella
write that the model provides a "welcome conceptual framework," but that
further work will be necessary to determine the effects of GMHT crops on
Monsanto Company Response to European Study in Science Magazine
European researchers will publish an article in the Sept. 1 edition of
Science magazine using a theoretical model to suggest that the planting of
herbicide-tolerant sugar beets could reduce the production of weed seed
and ultimately decrease bird populations. The article claims that
herbicide-tolerant crops reduce weeds that provide important sources of
food for birds, including skylarks.
It is important to understand that this is not an issue of biotechnology.
It is an issue of weed control, whether through biotechnology or other
methods. This mathematical model, and any conclusions drawn from it, must
be viewed with caution, because it does not reflect real farming
conditions. Most importantly, the study ignores the value of weed control
to farmers who can lose valuable yields and the ability to effectively
grow their crops.
When reviewing this model, the following facts should be considered:
* This report describes predictions that are not specifically related to
biotechnology, but are equally applicable to any agricultural practice
designed to manage weeds. The use of biotechnology as a basis for modeling
is irrelevant. It is possible to achieve the same level of weed control,
and hence the same impact, using traditional pesticides, tilling and other
* This report is based on a theoretical model that uses basic assumptions
that are inconsistent with real agricultural practices. It is
inappropriate and misleading to draw conclusions about the natural
environment based on a single, non-validated theoretical model that
employs untested assumptions.
* Contrary to this theoretical report, data from other scientists who have
conducted field studies on herbicide-tolerant sugar beets has shown that
herbicide-tolerant plants allow farmers to maintain weeds longer in sugar
beet fields, which could offer greater resources at a time of year when
for birds is scarce.
* Agricultural practices that improve the yield per acre actually prevent
additional land from coming under cultivation, preserving the best
wildlife environments in their natural state and protecting indigenous
habitats for birds and other wildlife.
* Furthermore, biotechnology crops like herbicide-tolerant crops, promote
reduced tillage systems which have been proven to improve wildlife habitat
for species ranging from birds to soil invertebrates. By using reduced
tillage, there is less soil disturbance and increased food supplies that
encourage higher densities of bird species in farmers’ fields.
* Herbicide tolerant crops can reduce the number of herbicide applications
for weed control, often replacing herbicides that can have negative
environmental effects. In a 2000 study by the National Center for Food and
Agricultural Policy, researchers showed that U.S. soybean growers, for
example, had decreased the number of applications of active ingredient
herbicides by 16 million applications, or roughly 20 percent.
* Weed control is especially important in growing sugar beets, as
scientists have proven that uncontrolled weeds can reduce sugar beet
yields by more than 90 percent.
* Finally, sugar beets are grown on a minor percentage of agricultural
acres. In terms of wildlife habitats, sugar beet fields represent an
inconsequential amount of habitat compared to more natural environments
and feeding grounds for birds, including undisturbed fields, natural
forests and waterways.
The following experts can help provide a field context and perspective to
the impact of biotech crops on wildlife.
Bill Palmer, Ph.D., Adjunct Professor/Research Scientist, Tall Timbers
Research Station - University of Georgia, Mississippi State University,
North Carolina State University 850/893-4153 ext. 226
Richard E. Warner, Ph.D., Assistant Dean of Research, College of
Agriculture, Consumer and Environmental Studies University of Illinois
Monsanto Company urges those who cover this to be careful in how the study
and its subject are treated. The study leaves many questions unanswered,
and it does not reflect how farmers truly grow their crops and protect
Please contact me with any questions or for additional comments. I can be
reached at 314/694-2883.
Scarlett Foster, Director, Public Affairs, Monsanto Company
BIO Statement Regarding Science Report on Biodiversity and Biotech Crops
CONTACT: Dan Eramian; Charles Craig; Lisa Dry
Thursday, Aug. 31, 2000 (202) 857-0244
(Dr. Val Giddings, vice president for food and agriculture of the
Biotechnology Industry Organization today issued the following statement
regarding a paper to be published in the September 1 issue of Science
titled "Predictions of Biodiversity Response to Genetically Modified
Herbicide Tolerant Crops."
WASHINGTON, D.C. (August 31, 2000)--"This report is a purely theoretical
model and cannot in any way be construed as a real world study. It has
everything to do with counting weeds, and nothing to do with
biotechnology," said Dr. Val Giddings, vice president for food and
agriculture for the Biotechnology Industry Organization (BIO).
"The authors sought to determine how weed populations respond to effective
weed control—a very common agricultural practice that is not unique to
biotech crops. In fact, farmers routinely strive to gain the highest
possible crop yields by reducing the number of weeds competing for the
same natural resources of water, soil nutrients and sunlight."
"On the second question, the impact of herbicide resistant crops on
biodiversity and specifically skylarks, we should consider that farmers’
concerns for the environment have led to numerous improved agricultural
practices. Both actual field experience and numerous studies have been
acknowledged by the National Academy of Sciences and the Environmental
Protection Agency as showing that crops improved through biotechnology
lead to greater biodiversity.
"Herbicide-tolerant crops, which are produced through biotechnology and
other means also promote reduced tillage systems which are proven to
improve wildlife habitat for species ranging from birds to soil
invertebrates. By using reduced tillage and leaving plant stubble standing
in the field, there is less soil disturbance and increased food supplies
for birds, including song birds."
"In fact, the greatest threat to biodiversity is loss of wildlife habitat
which is often is converted to low-yield agriculture. Technologies such as
biotechnology that increase productivity on existing cultivated acreage
will help meet increasing world food demand and reduce pressure to
encroach further on wildlife habitat."
The Biotechnology Industry Organization (BIO) is the world’s largest
organization to serve and represent the biotechnology industry. BIO’s
leadership and service-oriented guidance have helped advance the industry
and bring the benefits of biotechnology to people everywhere. BIO
represents more than 900 biotechnology companies, academic institutions,
state biotechnology centers and related organizations in all 50 U.S.
states and more than 27 other nations. BIO members are involved in the
research and development of health care, agricultural and industrial and
environmental biotechnology products.
Experts on avian wildlife:
Geoffrey Hill, Ph.D., Associate Professor, Auburn University, Alabama,
Bill Palmer, Ph.D., Adjunct Professor/Research Scientist, Tall Timbers
Research Station - Univ. of Georgia, Mississippi State Univ., North
Carolina State Univ., 850-893-4153 ext. 226
Richard E. Warner, Ph.D., Assistant Dean of Research College of
Agriculture, Consumer and Environmental Studies University of Illinois,